Rottnest Island in May

October through April delivers Rottnest's best weather. Water temperatures peak at 24°C in February, air temperatures hover around 26°C, and the quokkas stay active throughout the day. December and January bring the biggest crowds – and the highest prices. Accommodation doubles in cost, ferries book out weeks ahead, and every beach fills by noon. The upside? Longest days and warmest water. March and April offer the sweet spot. Still warm enough for swimming, but school's back in session. Hotel rates drop by 30%, and you can actually find a quiet spot at The Basin. Winter (June to August) sees water temperatures drop to 18°C, but the island takes on a different character. Fewer tourists, dramatic storms, and the southern right whales migrate past the coast. Pack layers – morning temperatures can hit 12°C before warming to 20°C by afternoon.